Block-signal system.



L. A. HAWKINS. BLOCK SIGNAL SYSTEM.

APPLICATION FILED MAR, 11, 1909.

- Patented Oct. 19, 1909.

2 SHEETS-SHEET 1.

ATTY:

L. A; HAWKINS.

BLOCK SIGNAL SYSTEM. summon FILED MAR. 11, 1909 2 SHEETS-SHEET 2.

ijj Wll u M g p IISZ'YE'NI'OH' I Lavamvaz A. .BY

1 1/7115155555' m \A mm.

AT 'T UNITED BATENT OFFICE,

LAURENCE A. HAWKINS, orsonn nncranx'nnw YORK, ASSIGNOB. TO- GENERAL ELECTRIC COMPANY, A conrona'rron or NEW YORK.

BLOCK-SIGNAL SYSTEM.

Tool! whom it may concern:

Be it known that I, LAURENCE A. HAW- runs, a citizen of the United States, residingatSchenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Block- Signal Systems, of which the following is a specification.

My invention relates to block signal, systems for electric roads having both rails conductively continuous for all currents, and consists in an improvement in the system disclosed in my prior application, Serial No. 329,347, filed August 6, 1906.

In that prior application I disclosed a system in which sources of alternating-current are connected across the rails at inte.rvals, the currents from adjacent sources differing in frequency, and rel'ays are connected across the rails in pairs between adjacent sources, the two relays ineachupair responding selectively to the currents inlthe twoadjacent sources, respectively. Since in such a system the usual insulated jointsare dispensed with, it is necessary, forv defining the block lengths, to rely upon the operation of a relay when a car reaches a certain position with respect thereto. As I pointed out in my prior application, it is possible by employingcnrrents of high frequency, such, for instance, as 250 and 300 cycles, and using a transformer of good regulation placed at the entrance of the block,'to define the limits of the block within a comparatively few feet.

In the system of my prior application, the use of high frequency currents is of particular value for obtaining the definiteness of block-length, but if it is desired to operate the signal mechanisms from the transmission circuit of the signal system, the use of highfrequency current has the objection of making necessary especially designed apparatus, which'is somewhat less efficient with respect to current consumption than similar apparatus designed for lower frequency.

The object of my present invention is to make it possible to employ currents of lower frequency without sacrificing the definiteness of the block-length or increasing the power consumption in the track circuits. My invention consists in the addition of an extra relay placed near to the source at the entrance of the block on the side on which a car approaches the source, and employing. this relay to controLthe signal for the block the extra relay which determines the point at which the signal goes to danger; and

since this relay may-be placed much nearer to the source than the other relays, the point at which it operates is fixed within correspondingly narrow limits, because the variation, under difierent weather conditions, of the point occupied by a car, when the relay operates, varies almost directly with the distance of the relay from the source. y

My invention will best be understood by reference to the accompanyingdrawings, in which Figure 1 shows diagrammatically a signal system arran ed inaccordance with my invention applie to one track of a doubletrack system, while Fig. 2 shows my invention a lied to a singletrack road.

In ig. 1, A represents the rails of an electric railway, which may both be bonded throughout their len th in the usual manner, sothat they are con uctively continuous for all currents. B and 13 represent alternating-current generators of different frequencies, as, for instance, of and 90 cycles. 6 b and 6 represent transmission wires, the wire b acting as common return for both frequencies. 0 and C represent transformers, the primaries of which are connected jointly with the two relays on the other side of the source. With this arrangement it is Specification of Letters Patent. -Pa1; e11ted ()(Jij. 19, 1909. p Application filed M rc 11,1609. Serial No. 482,637.

to the transmission wires, while theirsecondaries are connected across the track in series with resistances or impedances 0. Adjacent transformers are connected to different pairs of line wires, so as to supply currents at different frequencies to the track rails. The resistances o are for the purpose of preventing saturation of the transformers by unbalanced power-current, and also for limiting the current drawn from a transformer when a car :stands across the secondary terminals. D to D represent the track relays. I have indicated these relays diagrammatically as of the two-phase induction type comprising a short-circuited secondary member (Z carrying the relay contacts, a primary'winding (1 connected across the track rails, and a second cooperating primary winding (Z supplied from the transmission circuit. Phase controlling devices. such-- as condensers (2?, may be employed, if necessary, to give a sufiicient phase displacement between the currents in the primary in sai in order to prevent saturation from un alanced power current. As is well known in the art, relays of this type having one winding supplied independent y of the track circuit with current of .a certain frequency will respond only .to current in the track of correspondin frequency. For instance, since the windings d of relays D, D and D? are supplied with current from the same generator B to which the transformer C is connected, these relays will respond to the current delivered to the" track by this transformer, but will not respond to current of the frequency of generator B Similarly relays D and D will respond to current from transformer C and not to current from transformer 0 Relays D and D have their track windings connected across the rails approximately midway between the-transformers C and C Relays D and D are similarly connected between transformer O and the transformer next to the left (not shown), which is of the same fre-' quency of transformer C The relay D is placed adjacent to tra'nsformer C on the side on which a car approaches the transformers. The direction of traffic is shown by the arrow. The distance from relay D to transformer C need -not be-more than 10% of the distance from the transformer of the relays B and-D It'is only essential that the distance between relay D and transformer C shall be great enough to insure that relay D shall always open its contacts before relay D is deenergized. Relay D is similarly placed with respect to transformer C The signals E and E are placed near relays l) and Dff, respectively, a few feet back of the points at which these relays are connected across the track. The signal E is controlled by relays D D and D while the signal E is controlled by relays D D and D. l/Vhile relays D and I) are shown as of the same type as the other relays, it. is not essential that these particular relays should be selective as to frequency, but it issufficient if they are not affected by the power-current.

The operation of the system is as follows. With no car in the block, the signals stand at clear, as indicated. A car approaching from the right shu'nts' the relay D" when its front wheels havepassed a few feet beyond the signalE and within a few feet of the track connections of relay.D. The shunting of relay D uts signal E at danger. When the front wheels of, the car have reached a point somewhere between relay D and transformer G the relay D supplied from transformer C is also shunted, introducing another break in the control circuit of signal E After the car has passed transformer C a certain distance relay D is again energizedi'but this does not clearthe signal E since the relay D remains deenergized. Be-' fore the I car reaches the point at which ,relays D and D are connected to the track,

assed "some distance beyond this the current delivered by this transformer to the track to rise to a sufficient amount for effectively reener 'izing the track winding of relay D. Befbr'e this occurs, the signal E has been put to dan or by the successive deenergizing of relays and D Y Two things should be noticed,first, that since the signal E is not cleared until the carhas passed some distance beyond transformer 0 while signal E was put at stopposition when the car passed it, there is a natural overlap in the system, which affords an additional measure of protection. In

many cases, as, for instance, on electric roads operating single cars with shortbraking distances, this overlap makes it possible to Y dispense entirely with the use of distant signals. This overlap is obtained without the use of an additional source of current for that pur ose simply by connecting the relay Dh'WhlCl CODUOlS the signal E across the rails of the same track circuit whicltsupplies the relay D controlling the signal E In the secondplace,.it should be noted that while the entering-end of the block is definitely fixed by thelocation of the extra relays close to the transformers, the-outgoingend is not so definitely fixed, since it is dependent upon the reenergi'zat'ion of a relay half a block-length from its source. This is not ordinarily of any importance, since it merely means a variation in the amount of overlap, and this overlap may be made greater under all conditions than the braking distance of theordinary interurban car. If at any time it becomes important to fix the outgoing-end. of the block as definitely as the entering-end, this can be done by adding another relay near the sourceat the exitend of the-block, and on the side on which a car leaves the source. transformers and track as shown in Fig. 2, in which fi ure, the control circuits are adapted for operation on a single-track road with trains running in both directions. In this figure three transformers are shown, transformers C and C supplying current of the same frequency, while intermediate transformer C? supplies to thetrack current of the other frequency. It will be noted that the relative connections of transformers C and (l are relatively reversed. This would also be shown in Fig. 1,

were it not that only twotransformers appear in this figure. The purpose of this retraffic from right to left, and signals E,

E and E proximately midway between ad acent transat signals E and E respectively,

reaches relay D although of the proper fre-' quency for operating the relay, will be in .cuit of signal brakin versal of connections of transformers C and C any current from transformer G which the wrong direction,that is, will produce a current in the-relay which tends to open its contacts, and will,'therefore, be on the side of safety. The signals-13 ,12 and E are for for trafiic from left to right. A pair of relays, as D and D, are placed apformers C and C while extra relays, l) and D are placed on each side of the transformer C Line relays F to F are indicated in this -figure for controlling the signals E to E". vIt will be seen that the cir E for instance, extends from line-wire 6, through the upper contact of line-relay F through signal mechanism E and through the lower contact of line-relay j F to line-wire 6 The signal E therefore, I l

stands at stop, whenever either relay F or F is deenergized. Relay F 3 is controlled by relays D, D and D while F 'is controlled by relays D, D and D Signal E is, therefore, at stop with a car at any point between relay D and a point beyond transformer O at a suflicient distance to allow rela D to be energized. Similarly, signal E is controlled by line-relays F and F which, in turn, are controlled by relays D D and D and by relays D, D and B, respectively, so that signal E is at stop Bosition with'a car anywhere between relay 1 and a point sufficiently beyond transformer C to enable relay D to be energized. Thus, it will besecn that a car passing signal E*, moving from left to right, throws signal E to stop, and, after advancing a few feet farther, throws signal Etto stop, signal E being already at stop. A car passing signal E, moving from riht to left, throws signal E to sto be ore it reaches transformer C, signal 5 being already at stop. If two cars moving in opposite directions should pass si 'nals E and E at the same time, they woiild be stopped The distance betweenj'signals E and E will ordi-- narily be sufficient for adequate protection on roads operating single cars in whichthe braking distance is comparatively short. For roads operating heavy trains, with long distances, it would ordinarily be: desirable that the control circuit for the sig- 'uals for one direction of traf ic should be 1 extended through the contacts ofanotherl line-relay, 0 asto extend the zone of control 1n the manner well understood in the art.

mechanisms are shown supplied from the generator B This is sometimes desirable in cases where one of the frequencies is stand ard, as 60 cycles, and the other is not, and there is an advantage in using standard apparatus. In other cases it is advantageous to supply a portion of the signal mechanisms from each of the two frequencies, as shown in Fig. 2, since this arrangement divides the load more equally between the two generators. r 1

My invention permits of various other modifications and adaptations to meet varying c -nditions, and accordingly I do-not desire to limit myself to the'particular connecprising signals for the tion. and arrangement of partsshown, but aim in the appended claims to cover all modifications whicl are within the scope of my invention.

I do not in this application make any claim tov a block signal system for railways having both rails conductively continuous for all currents, in which adjacent sources of current for the't-rack circuits are of different character and the relays'are selectively responsive to current of one character only, nor dol make any claim to a system for such railways having the relays arranged in pairs between adj acent. sources, since these matters form the subject-matter of my prior application, Serial No. 323,347, above referred to.

\V hat I claim asnew, and desire to secure by Letters Patent of the United States, is,'

1. ln combination with acent sources, and selectively responsive to an electric railway, having both rails conductively contlnuous current from the two adjacent sources re- 1 and a relay connected across the rails near a. source on the side on which the cars approach said source and controlling a si 'nal jointly with the pair of. relays on the e her side of said source. j

' 2. In combination with an electric railway having both rails conductively continuous for all currents, a block si nal system C0111: blocks, sources of alternating current connected across the rails at intervals, the currents from adjacent sources didering in frequency, lays connected across the ra spectivel-y,

ils between adacent sources and selectively responsive to current from the adjacent sources respectively, and a relay connected across the rails near 'a source on the side on which the cars approach said sourcc'and controlling a signal jointly with the pair of relays on the other side of said source.

3. In combination with an electric railway It will be noted that in Fig; 1 all the signal having both rails conductively continuous a pair of re-- for all currents, a block signal system com-- prising signals for. the 1b ocks, sources of alternating current connected across the rails at intervals, the currents from adjacent sources difi'eringin'character, a pair of relays connected across the rails between adacent.s'ources, and selectlvely'responsive to current from the twoadjacent sources re spectlvely, and a relay connected across the rails near a source on the, slde on which the cars approach said sourceand controlling asignal' ointly with the pair of .relays on the other-side of said source, said signal being located adjacent to said relay,

4. In combination with an electric rail way having both rails conductively continuous for all currents, a block signal system comprising signals for the blocks, sources of. alternating current connected across the rails at intervals, the currents from adja-.

cent sources differing in frequency, a pair of relays connected across the rails between adjacent sources and selectively responsive to current from the two adjacent sources respectively, and a relay connected across the ralls near a source on the side on which the cars approach said source and controlling a signal jointly with the pairof relays on the other side of said source, said signal being located adjacent to said relay.

5'. In combination with an electric railway having .both rails conductively continuone for all currents, a block signal system comprising signals for the blocks, sources of alternating current connected across the rails at intervals, the currents from adjacent sources difl'ering in character, and'two relays connected across the rails on opposite sides of a source, one at a'distance therefrom and the other adjacent thereto, the'further relay being responsive only to current from said source and both relays controlling the same signal.

6. In combination with an electric railway. having both rails conductively continuous for all currents, a block signal system comprising signals for-the blocks, sources of alternating current connected across the .rails, at intervals, the currentsfrom adjacent sources difl'ering in frequency, and two relays connected across the ra ls on opposite semes- .v.s ides of a source one at a distance therefrom way having both rails conductively continuous for all currents, a block signal system comprising signals for the blocks, sources of alternating current connected across the rails at intervals, the currents from adjacent sources differing in frequency, and two relays connected across the rails-on opposite sides of a source one at a distance therefrom and the -other adjacent thereto, both responsive only to currentfrom said source and both controlling the same signal, the said signal being located near the relay adjacent to the source. r

9. In combination with an electric railway having both rails conductively continuous for all currents,a block si 'nal system for controlling trafiic in both directions on in single track comprising sources of alternating current connected across the rails at intervals, the currents from adjacent sources differing in character, track relays connected across the rails in pairs between adjacent sources, the relays of each pair being solectively responsive to current from the two adjacent sources respectively, two track relays near each source on opposite sides theretraflic near to and controlled by the last named relays res ectively, the direction of a nating current connected across the rails at intervals, the currents from adjacent sources difierin in character, track relays connected across t e rails in pairs between adjacent sources, the relays 'of each pair being scof, and signals for opposite directions of--.

lectiv'ely responsive to. current from the two ad acent sources respectively, two track relays near each source'on. opposite sides thereof, and signals-for opposlte directions of traflic'near to and controlled by the last named relays res ectivcly, the direction of traffic controlled y each signal being from the. relay toward the adjacent source and each signal being control ed jointly by the relay which it is near and the next two pairs of relays beyond the adjacent source.

11. In combination wlth an electric railway having both rails conductively continuous for all currents, a block signal system comprising signals for, the blocks, sources of alternating current connected across the rails at intervals, the currents from adjacent sources differmg in character, relays connected aorossthe rails between two adjacent corn rislng signals for the blocks, sources 10 of a ternating current connected across the rails at intervals, the currents from adjacent 'sources difiering in character, relays connected across the rails between adjacent sources, and a relay connected across the 15. rails near to and in the rear of the-rear source of'said two sources and controlling a signal jointly with the first-mentioned relays, the signal being placed near the latter relay.

13. In a block si nal system' comprising signals for the bloc s with controlcircuits therefor, a source of alternating current connected across the track, a track relay at a distance from the source. supplied with cur- 25 rent therefrom throu h the track rails, and

a second track relay avinga winding con- 14:. In combination ,nected across the rails at a point between 'thesource and the first relay,rthe contacts of the two relays being connected in different control c rcuits.

with an electric railway havin both rails conductively continu ous'for all currents, sources of alternating current connected across the rails at intervals, a air of track relays supplied with current 1'0111 the rails between each two adjacent sources, each of said relays r sponding sources, signals each controlled by one of said pairs of relays, and a relay connected A across'the rails between a source and a pair of relays and controllin the signal controlled by the pair .of re ays on the other side of said source, whereby the zones of control of adjacent signals are caused to overlap. In witness whereof, I have hereunto set my hand this 9th day of March, 1909.

- LAURENCE A. HAWKINS. Witnesses:

BENJAMIN B. HULL, v HELEN Onrom).

'to current from only one of the adjacent, 

